This invention generally relates to portable towers for raising lights or tools above the ground and more particularly to portable collapsible towers with at least one stationary tower member and at least one movable tower member that is extendable and retractable with respect to the at least one stationary tower member. Portable towers are typically used at construction or other work sites to raise lights or tools above the ground.
The use of portable towers to support lights or tools is well known in the art. Known portable towers usually are transported on and supported by a portable vehicle. Typically, the portable towers include a number of hollow, concentrically oriented tower members. The portable tower includes a stationary tower member fixed to the vehicle frame and one or more movable tower members extendable and retractable, relative to the stationary tower member, in a telescoping manner.
It is also well known in the art to extend and retract the one or more movable tower members using a cable system located in the hollow interiors of the tower members. Such a known cable system is generally comprised of one or more cables in combination with a number of pulleys with a cable connected to a tension altering device, usually a hand operated crank or winch mounted on the vehicle. By moving the crank in a first direction, the tension in the one or more cables is increased causing the one or more movable tower members to extend in a telescoping manner, relative to the stationary tower member. Movement of the crank in a second direction retracts the one or more movable tower members in a telescoping manner, relative to the stationary tower member.
There are a number of problems associated with the known portable towers. First, it is difficult to repair and troubleshoot known cable systems. Currently, if a cable breaks or another component of the cable system fails, making it necessary to gain access to the system, the portable tower must be disassembled. When the tower is disassembled for repair, it can not be used. Troubleshooting and repairing the tower can take a significant period of time. Significant portable tower downtime can negatively affect productivity at a work site or another location where use of the tower is required.
Second, because known cable systems are hidden from view, it is burdensome to conduct periodic inspections of the cable system to anticipate cable system component failure. In order to conduct such periodic inspections, disassembly of the tower is required. Because disassembly of the tower is required, such periodic inspections may not be conducted at all or may only be conducted sporadically. As a result, a component part failure, which could have been anticipated by periodic inspection, may occur and damage the tower.
Finally, operation of known portable towers can be complicated. In addition to the movable and stationary tower members and cable system, known portable towers may also include a number of latches in combination with one or more winches. In operation, each latch and winch must be operated in the proper sequence in order to extend and retract the tower members.
The foregoing illustrates limitations known to exist in present portable towers and associated methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.